1. Field of the Invention
The present invention relates to a method for manufacturing a piezoelectric actuator and an ink-jet head.
2. Description of the Related Art
An example of a piezoelectric actuator for an ink-jet head is disclosed in Japanese Patent Application Laid-open No. 11-314365. This piezoelectric actuator comprises a substrate (elastic film) provided so as to close the openings in pressure chambers communicated with nozzle openings in a channel forming body of the ink-jet head and has a structure in which a lower electrode, a piezoelectric film, and an upper electrode are laminated in this order on the substrate. When an electric field is applied between the lower electrode and upper electrode, the substrate bends by the deformation of the piezoelectric film, a pressure is applied to the ink present inside the pressure chambers, and the ink is discharged from the nozzle openings.
A method called an aerosol deposition method (AD method), such as described, for example, in Japanese Patent Application Laid-open No. 2001-152360 has been suggested as a method for the manufacture of the above piezoelectric actuators. In this method, a dispersion (aerosol) of fine particles of a piezoelectric material such as lead zirconium titanate (PZT) in a gas is ejected toward a substrate surface and a piezoelectric film (piezoelectric layer) is formed by collisions of the fine particles with the substrate and deposition thereonto.
In the above-described AD method, the particles blown on the substrate collide with the substrate and adhere thereto, while being crushed. Therefore, a piezoelectric film having a sufficient piezoelectric characteristic cannot be obtained by the size reduction of the particles and occurrence of lattice defects due to collisions. For this reason, the piezoelectric film has to be subjected to annealing in order to obtain a piezoelectric characteristic necessary to bend the substrate sufficiently. However, when the inventor actually formed a piezoelectric layer on a substrate by the AD method and then conducted annealing, the piezoelectric characteristic degraded.